Squint/ Strabismus Treatment Squint/ Strabismus Treatment |
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EYE SPECIALIST CLINIC PTE LTD
 
 
Eye Clinic & Optometry Centre for Children and Adults

Squint/ Strabismus Treatment

What is Strabismus?

Strabismus, or squint, is a condition in which the eyes are not properly aligned with each other. One eye may look straight ahead, while the other eye turns inward, outward, or downward.

Strabismus is a common condition among children. However, it can also occur later in life or during adulthood.

Strabismus occurs equally in males and females. It may run in families (inheritance); but there are also many cases where no family history is present.

 

What causes strabismus?

The exact cause of strabismus is not fully understood.

It is commonly found in children with disorders such as cerebral palsy, Down syndrome, prematurity, hydrocephalus and brain tumours. However, vast majority of children with strabismus do not have these problems.

Many of them do have a family history of strabismus.

A cataract eye or eye injury that affects vision (severe amblyopia or lazy eye) can also result in strabismus.

 

How do the Eyes Work Together?

The brain’s ability to see three-dimensional objects depends on proper alignment of the eyes. When both eyes are properly aligned and aimed at the same target, the visual portion of the brain fuses the forms into a single image. When one eye turns inward, outward, upward, or downward, two different pictures are sent to the brain. This causes loss of depth perception and binocular vision and there may be double vision.

 

What are the signs?

The main sign is the eye is not straight.

 

Common Types of Strabismus

Including 1. Esotropia 2. Exotropia 3. Hypotropia 4. Hypertropia
 

1. ESOTROPIA

Esotropia (convergent squint) is the most common form of strabismus (squint) in infants. In the case of esotropia, one eye deviates inward toward the nose while the other fixates normally. It is commonly known as “cross-eye”. It happens equally in males and females and is sometimes hereditary. Esotropia can also affect teenagers and adults, and it is usually related to systemic conditions such as high blood pressure, diabetes, strokes, or brain injuries

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Types of Esotropia

  • Pseudoesotropia (false esotropia) is actually the physical appearance of cross-eye when the eyes are perfectly aligned. This is known as pseudostrabismus. Infants and young children often have a wide, flat nose with a fold of skin at the inner eyelid that makes the eyes appear crossed. This appearance usually disappears as the child grows.
     
  • Congenital or infant esotropia can be present at birth or may develop anytime during the first 6 months of life. Although it is common for an infant’s eyes to be intermittently misaligned, if the condition persists beyond the first few months, it should be checked by a physician. One to 2 percent of children have congenital esotropia, and the condition usually does not improve with age. Surgical correction is usually recommended between 6 and 14 months of age.
     
  • Accommodative esotropia is a common form that occurs in farsighted children, usually 2 years old or older. Young children can often overcome farsightedness by focusing their eyes to adjust to the condition, but the effort required for this focusing causes the eyes to cross. Eyeglasses can reduce the focusing effort and sometimes straighten the eyes. In addition, special eyedrops, ointments, and lenses called prisms may also be effective. Eye exercises can also be helpful, especially in older children. Sometimes bifocals can correct the excessive turning in of the eyes for close work.
     
  • Acquired esotropia occurs after infancy. Children who have been farsighted and have not had glasses, or children who were responsive to glasses but later developed an additional eye-crossing, are the most commonly affected. Children with acquired eye-crossing require prompt evaluation and treatment to correct the deviation and to restore binocular vision.

The causes of some forms of esotropia are not fully understood. There are six muscles that control eye movement, four that move it up and down and two that move it side to side. All these muscles must be coordinated and working properly in order for the brain to see a single image. When one or more of these muscles doesn’t work properly, some form of strabismus may occur. Strabismus is more common in children with disorders that affect the brain such as cerebral palsy, Down syndrome, hydrocephalus, and brain tumors.

What are the symptoms of esotropia?

Symptoms of esotropia are decreased vision, double vision, and misaligned eyes. Children with esotropia do not use their eyes together and often squint in bright sunlight or tilt their heads in a specific direction to use their eyes together. They may also rub their eyes frequently. Children rarely tell you they are experiencing double vision, although they may close one eye to compensate for the problem. You may also notice signs of faulty depth perception.

When a young child has strabismus, the child’s brain may learn to ignore the misaligned eye’s image and see only the image from the best-seeing eye. This is called amblyopia, or lazy eye, and results in a loss of depth perception. In adults who develop strabismus, double vision sometimes occurs because the brain has already been trained to receive images from both eyes and cannot ignore the image from the turned eye.

 

Treatment for esotropia

Treatment depends on the type of esotropia. Accommodative esotropia can be treated successfully by correcting a refractive error with glasses, patching to force the use of the less-preferred eye, or other forms of therapy. Congenital and acquired esotropia usually require surgery for proper and permanent correction.

The surgeon makes a small incision in the tissue covering the eye in order to reach the eye muscles. Then either tight inner muscles are placed farther back to weaken their pull, or the loose outer muscles are tightened by shortening their length to allow the eye to move outward. The procedure is usually done under general anesthesia. Recovery time is rapid, and normal activities can usually be resumed within a few days. Following surgery, corrective eyeglasses may be needed and, in some cases, further surgery is required later to keep the eyes straight.

As with all surgery, there are some risks, but strabismus surgery is usually a safe and effective operation.

 

2. EXOTROPIA

Exotropia (divergent squint) is another common form of strabismus (squint). In the case of exotropia, one eye deviates outward (away from the nose) while the other fixates normally. Exotropia often begins between the ages of 2 and 4. It occurs equally in males and females and is sometimes hereditary. The condition can also develop later in life.

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Types of Exotropia

Exotropia may be congenital (present at birth) or acquired. The acquired forms of exotropia include intermittent exotropia, sensory exotropia, and consecutive exotropia.

 

What are the symptoms of exotropia?

The earliest sign of exotropia is usually a noticeable outward deviation of the eye. This symptom may at first be intermittent, occurring when a child is daydreaming, not feeling well, or tired. The deviation may also be more noticeable when the child looks at something in the distance. Squinting or frequent rubbing of the eyes is also common with exotropia. Your child probably will not mention seeing double, i.e., double vision. However, he or she may close one eye to compensate for the problem.

Generally, exotropia progresses in frequency and duration. As the disorder progresses, the eyes will start to turn out when looking at close objects as well as those in the distance. If left untreated, the eye may turn out continually, causing a loss of binocular vision.

In young children with any form of strabismus, the brain may learn to ignore the misaligned eye’s image and see only the image from the best-seeing eye. This is called amblyopia, or lazy eye, and results in a loss of depth perception. In adults who develop strabismus, double vision sometimes occurs because the brain has already been trained to receive images from both eyes and cannot ignore the image from the turned eye.

 

Treatment for exotropia

A comprehensive eye examination including an ocular motility (eye movement) evaluation and an evaluation of the internal ocular structures will allow an eye doctor to accurately diagnose the exotropia. Although glasses and/or patching therapy, exercises, or prisms may reduce or help control the outward-turning eye in some children, surgery is often required.

The most reliable treatment for exotropia is usually eye muscle surgery, but this is often preceded by eye patching and/or eyeglass therapy, especially if amblyopia (lazy eye) is present. This therapy is designed to maximize the existing vision in the weaker eye. In some children, this therapy may eliminate the need for surgery. There is a rare form of exotropia known as “convergence insufficiency” that responds well to therapy. This disorder is characterized by an inability of the eyes to work together when used for near viewing, such as reading. Instead of the eyes focusing together on the near object, one deviates outward.

Surgery is usually recommended if the exotropia is present for more than half of each day or if the frequency is increasing over time. Surgery is also indicated if a child has significant exotropia when reading or viewing near objects or if there is evidence that the eyes are losing their ability to work as a single unit (binocular vision). If none of these criteria are met, surgery may be postponed pending simple observation with or without some form of eyeglass and/or patching therapy. In very mild cases, there is a small chance that the exotropia will diminish with time.

The surgical procedure for the correction of exotropia involves making a small incision in the tissue covering the eye in order to reach the eye muscles. The appropriate muscles are then repositioned in order to allow the eye to move properly. The procedure is usually done under general anesthesia. Recovery time is rapid, and most people are able to resume normal activities within a few days. Following surgery, corrective eyeglasses may be needed and, in many cases, further surgery is required later to keep the eyes straight.

When a child requires surgery, the procedure is usually performed before the child attains school age. This is easier for the child and gives the eyes a better chance to work together. As with all surgery, there are some risks. However, strabismus surgery is usually a safe and effective treatment.

 

3. Others

There are other types of squint depending on the direction in which the eye turns.

Hypotropia- where the eye turns downwards

Hypertropia – where the eye turns upwards

Hypertropia and hypotropia are less common than esotropia and exotropia.

 

What is pseudostrabismus?

This is the false appearance of misaligned eyes. The eyes may look crossed in but are actually straight.

 

Pseudoesotropia

Pseudoesotropia (false esotropia) is actually the physical appearance of cross-eye when the eyes are perfectly aligned. Infants and young children often have a wide, flat nose with a fold of skin at the inner eyelid that makes the eyes appear crossed. This appearance usually disappears as the child grows.

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True LEFT esotropia: The reflection of the light is not symmetrical in both eyes.

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Pseudostrabismus: The light reflection is symmetrical in both eyes although the eyes appear crossed in.

 

Pseudoexotropia

Pseudoexotropia (false exotropia): The eyes appear to be wandering out but are actually straight. While less common than pseudoesotropia, it also is often due to facial structures. Children with widely set eyes can appear as if their eyes are drifting out.

squint-2

True exotropia: The reflection of the light is not symmetrical in both eyes. Right eye has drifted out.

An infant’s eyes may drift in or out at times, but this small variable alignment is perfectly normal during the first few months. When a baby begins focusing on the environment at about two or three months of age, the eyes should be straight most or all of the time.

 

How is strabismus treated?

In some cases, eyeglasses can be prescribed to straighten the eyes. Other treatments may involve surgery to correct the unbalanced eye muscles.

 

Surgical Correction of Strabismus/ Squint

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Right Esotropia: Before surgery (the reflections of the light are not symmetrical)

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After surgical correction (the reflections of the light are symmetrical). Eyes are straight.

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Left Esotropia: Before surgery (the reflections of the light are not symmetrical)

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After surgical correction (the reflections of the light are symmetrical). Eyes are straight.

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Right Esotropia: Before surgery (the reflections of the light are not symmetrical)

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After surgical correction (the reflections of the light are symmetrical). Eyes are straight.

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Right exotropia: Before surgery

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After surgery: Eyes are straight

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Left exotropia: Before surgery

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After surgery: Eyes are straight